Automation of packer inflation

ABSTRACT

The disclosure provides for a method for setting an inflatable packer. The method includes positioning an inflatable packer within a borehole, and pumping fluid into an inflatable element of the inflatable packer using a pump that is driven by a motor. The method includes measuring pressure of the inflatable element, determining a derivative of the measured pressure with respect to time, and determining onset of restraining of the inflatable element has occurred. Upon or after determining the onset of restraining, the method includes turning off the motor or slowing down an rpm of the motor. The disclosure also provides for a system, including a computer readable medium with processor-executable instructions stored thereon that are configured to instruct a processor to execute a pressure control algorithm to control a speed of the motor in response to pressure measurement data from the pressure sensor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 62/900,993 (pending), filed on Sep. 16, 2019, theentirety of which is incorporated herein by reference.

FIELD

The present disclosure relates to methods, apparatus and systems forautomation of packer inflation.

BACKGROUND

During oil and gas drilling and production operations, packers aresometimes used to isolate sections of wellbores to carry out variousprocedures. Packers are inserted into a wellbore and then expanded toisolate a target interval of the wellbore. Inflatable packers are a typeof packer that are expanded by pumping a fluid into a bladder of thepacker. Inflatable packers are used in open or cased wellbores, and maybe run on wireline, pipe or coiled tubing. In preparation for settingthe packer, a drop ball or series of tubing movements are generallyrequired, with the hydraulic pressure required to inflate the packerprovided by applying surface pump pressure.

One application of inflatable packers is in formation testing orevaluation. Formation evaluations are performed to measure and analyzethe properties of the formation fluid therein, including assessing aquantity and producibility of fluids (e.g., oil) therein. Formationevaluations can be used to determine various actions, such as theviability of a formation for production, as well as which interval(s) ofa wellbore should be targeted for production purposes.

The inflation of packers, such as those of formation testing tools,typically requires operators to specify a pumping motor speed in orderto control the rate of inflation of the packer and the desired inflationpressure at which the packers are engaged with formation or casingaround the wellbore. That is, the rate of inflation and the timing ofwhen to stop and start inflation is controlled. Upon receiving controlcommands, the motor that drives the pump is operated at the speedspecified by the control command until the desired inflation pressure isreached. After the desired inflation pressure is reached, the motor iscontinuously operated at a reduced speed (i.e., ramping down) for,typically, a few seconds until the motor is completely stopped. Largeovershoots in pressure into the packers result from the additional timewithin which the motor is operated. Overshoots in pressure canpermanently damage and/or deform the packer elements. The size ofovershoot depends on the motor speed and the time that it takes to rampdown the motor speed. While a reduction of overshoot pressure may beachieved by specifying a slower motor speed at the beginning of theinflation process, it would also prolong the time required to inflatethe packers.

BRIEF SUMMARY

One embodiment of the present disclosure includes a method for settingan inflatable packer. The method includes positioning an inflatablepacker within a borehole, and pumping fluid into an inflatable elementof the inflatable packer using a pump that is driven by a motor. Themethod includes measuring pressure of the inflatable element, anddetermining a derivative of the measured pressure with respect to time.The method includes determining onset of restraining of the inflatableelement has occurred when the derivative is equal to or greater than aderivative threshold. Upon or after determining the onset ofrestraining, the method includes turning off the motor or slowing downan rpm of the motor.

Another embodiment of the present disclosure includes a system forsetting an inflatable packer. The system includes an inflatable packer,including an inflatable element. A pump is in fluid communication withthe inflatable element. A motor is coupled with the pump to drive thepump. A pressure sensor between the pump and the inflatable element ispositioned to measure pressure of the inflatable element. A motorcontroller is coupled with the motor. The motor controller includes aprocessor, a computer readable medium in communication with theprocessor, and processor-executable instructions stored on the computerreadable medium that instruct the processor to execute a pressurecontrol algorithm to control a speed of the motor in response topressure measurement data from the pressure sensor.

Another embodiment of the present disclosure includes a computerreadable medium including processor-executable instructions storedthereon. The processor-executable instructions are configured toinstruct a processor to execute a pressure control algorithm to controla speed of a motor in response to pressure measurement data.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the features of the apparatus, systems andmethods of the present disclosure may be understood in more detail, amore particular description is provided with reference to theembodiments thereof which are illustrated in the appended drawings thatform a part of this specification. It is to be noted, however, that thedrawings illustrate only various exemplary embodiments and are thereforenot to be considered limiting of the disclosed concepts as it mayinclude other effective embodiments as well.

FIG. 1A depicts a wellbore.

FIG. 1B depicts the wellbore of FIG. 1A with an inflatable packerpositioned therein, with the inflatable packer uninflated.

FIG. 1C depicts the wellbore of FIG. 1B with the inflatable packerinflated.

FIG. 1D is a schematic of a pumping system for inflating a packer.

FIGS. 2A-2C are graphs of packer pressure, setline valve position, andmotor speed, respectively, each during packer inflation in a first testcase (Case 1) performed without using the methods, systems, or apparatusdisclosed herein.

FIGS. 3A-3C are graphs of packer pressure, setline valve position, andmotor speed, respectively, each during packer inflation in a second testcase (Case 2) performed without using the methods, systems, or apparatusdisclosed herein.

FIGS. 4A-4C are graphs of packer pressure, setline valve position, andmotor speed, respectively, each during packer inflation in a third testcase (Case 3) performed without using the methods, systems, or apparatusdisclosed herein.

FIGS. 5A-5C are graphs of packer pressure, setline valve position, andmotor speed, respectively, each during packer inflation in a fourth testcase (Case 4) performed without using the methods, systems, or apparatusdisclosed herein.

FIGS. 6A-6C are graphs of packer pressure, setline valve position, andmotor speed, respectively, each during packer inflation in a fifth testcase (Case 5) performed without using the methods, systems, or apparatusdisclosed herein.

FIGS. 7A-7C are graphs of packer pressure, setline valve position, andmotor speed, respectively, each during packer inflation in a sixth testcase (Case 6) performed without using the methods, systems, or apparatusdisclosed herein.

FIGS. 8A and 8B are flow charts of methods of inflating a packer.

FIG. 9A is a graph of packer pressure of Case 1 showing a detected onsetof packer restraint, as indicated by an asterisk.

FIG. 9B is a graph of a pressure derivative of the packer pressure ofCase 1, as obtained by applying an S-G derivative filter to the data ofCase 1, with the broken line indicating a threshold of the pressurederivative.

FIG. 10A is a graph of packer pressure of Case 2 showing a detectedonset of packer restraint, as indicated by an asterisk.

FIG. 10B is a graph of a pressure derivative of the packer pressure ofCase 2, as obtained by applying an S-G derivative filter to the data ofCase 2, with the broken line indicating a threshold of the pressurederivative.

FIG. 11A is a graph of packer pressure of Case 3 showing a detectedonset of packer restraint, as indicated by an asterisk.

FIG. 11B is a graph of a pressure derivative of the packer pressure ofCase 3, as obtained by applying an S-G derivative filter to the data ofCase 3, with the broken line indicating a threshold of the pressurederivative.

FIG. 12A is a graph of packer pressure of Case 4 showing a detectedonset of packer restraint, as indicated by an asterisk.

FIG. 12B is a graph of a pressure derivative of the packer pressure ofCase 4, as obtained by applying an S-G derivative filter to the data ofCase 4, with the broken line indicating a threshold of the pressurederivative.

FIG. 13A is a graph of packer pressure of Case 5 showing a detectedonset of packer restraint, as indicated by an asterisk.

FIG. 13B is a graph of a pressure derivative of the packer pressure ofCase 5, as obtained by applying an S-G derivative filter to the data ofCase 5, with the broken line indicating a threshold of the pressurederivative.

FIG. 14A is a graph of packer pressure of Case 6 showing a detectedonset of packer restraint, as indicated by an asterisk.

FIG. 14B is a graph of a pressure derivative of the packer pressure ofCase 6, as obtained by applying an S-G derivative filter to the data ofCase 6, with the broken line indicating a threshold of the pressurederivative.

FIG. 15 is a flow diagram of a real-time adaptive and automated pressurecontrol algorithm.

FIG. 16 is a flow diagram of real-time detection of onset ofrestraining.

Methods, apparatus, and systems according to present disclosure will nowbe described more fully with reference to the accompanying drawings,which illustrate various exemplary embodiments.

DETAILED DESCRIPTION

One or more specific embodiments of the present disclosure will bedescribed below. These described embodiments are examples of thepresently disclosed techniques. Additionally, in an effort to provide aconcise description of these embodiments, all features of an actualimplementation may not be described in the specification. It should beappreciated that in the development of any such actual implementation,as in any engineering or design project, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which may vary from one implementation toanother. Moreover, it should be appreciated that such a developmenteffort might be complex and time consuming, but would still be a routineundertaking of design, fabrication, and manufacture for those ofordinary skill having the benefit of this disclosure.

When introducing elements of various embodiments of the presentdisclosure, the articles “a,” “an,” and “the” are intended to mean thatthere are one or more of the elements. The terms “comprising,”“including,” and “having” are intended to be inclusive and mean thatthere may be additional elements other than the listed elements.Additionally, it should be understood that references to “oneembodiment” or “an embodiment” of the present disclosure are notintended to be interpreted as excluding the existence of additionalembodiments that also incorporate the recited features.

The present disclosure includes adaptive and automated methods,apparatus and systems for reducing or preventing overshoot pressureduring packer inflation, and for maintaining a desired inflationpressure of packers.

With reference to FIG. 1A, wellsite 100 is depicted, including wellbore102 intersecting formation 104 beneath surface 106. Wellbore 102 may, ofcourse, include any of various typical components of a wellbore, such ascasing. Wellbore 102 has potential target interval 108. For example,target interval 108 may be an interval of formation 104 upon which it isdesired to perform formation testing.

With reference to FIG. 1B, inflatable packer 118 is positioned withincavity 110 of wellbore 102, such that inflatable packer 118 intersectswith target interval 108. Inflatable packer 118 includes bladders 120,which are, in FIG. 1B, in a non-expanded configuration. Inflatablepacker 118 is coupled with, integrated into, or a portion of string,between upper string portion 114 a and lower string portion 114 b. Forclarity and simplicity, the entire string is not shown.

With reference to FIG. 1C, bladders 120 of inflatable packer 118 areexpanded, such that bladders 120 engaged with the walls (e.g., formationand/or casing) of wellbore 102. With bladders 120 engaged with thewellbore 102, isolated wellbore section 122 is defined as a volume ofspace that at least partially overlaps with target interval 108. Whenused during formation testing, for example, wellbore section 122provides dead volume for filtrate and formation fluid 116 to flow intowellbore section 122.

With reference to FIG. 1D, a schematic showing certain componentsassociated with the inflation of the inflatable packers is shown. Oneskilled in the art would understand that the systems disclosed hereinare not limited to the components or arrangement of components shown inFIG. 1D. As shown in FIG. 1D, inflatable packer 118 includes twobladders 120. Each bladder 120 is fluidly coupled with pump 121 throughfluid conduits 125, also referred to as setlines. Valve 131, alsoreferred to as a setline valve, is positioned within conduits 125 toregulate the flow of fluid from pump 121 into bladders 120. Valve 131may be, for example, a solenoid valve. Pressure sensors 129 arepositioned to monitor the pressure within bladders 120 and/or alongconduits 125. The pressure sensors are not limited to being positedwhere shown in FIG. 1D, and may be located at another position betweenpump 121 and bladders 120. Pressure sensors 129 may be in data and/orelectrical communication with motor 123 via data communication lines 127(e.g., copper wire, fiber optics, or another data communication line).While the data communication is shown as occurring over lines 127, oneskilled in the art would understand that the data communication may alsobe wireless in other embodiments. Furthermore, while shown incommunication with motor 123, pressure sensors 129 may be incommunication with a controller that is, in-turn, in communication withmotor. For example, motor 123 may be an electric motor, and may becontrolled by a variable frequency drive (VFD), and pressure sensors 129may be in data communication with the VFD or with a computer, programmedlogic controller (PLC), or other controller that is in communicationwith the VFD. As shown in FIG. 1D, controller 143 is coupled with and/orin communication with motor 123, and is configured to control the speedthereof. Controller 143 may be or include a computer, a PLC, a VFD, orcombinations thereof. Controller 143 includes firmware 145 configured tocontrol the operation of motor (e.g., the speed of motor). Firmware 145may be or include the Savitzky-Golay polynomial filter and the adaptiveand automated pressure control algorithm disclosed herein, such thatfirmware 145 controls the speed of motor 123 in response to pressuredata from pressure sensors 129.

Motor 123 drives pump 121 to cause pump to pump fluid (e.g., gas, suchas air) into bladders 120 to inflate bladders. During inflation ofbladders 120, sensors 129 may monitor pressure and transmit pressuremeasurements to motor 123 or to a controller in communication with motor123, such that operation of motor 123 is responsive to the pressuremonitored by sensors 129. Once bladders 120 contact the walls of thewellbore, as shown in FIG. 1C, the rate of pressure increase risesbecause the bladders 120 cannot expand beyond the walls of the wellbore.

FIGS. 2A-7C are graphs of several examples of packer inflations, wherethe adaptive and automated methods, apparatus and systems for reducingor preventing overshoot pressure disclose herein are not used. In FIGS.2A-7C, psi, % valve opening, and rpm are plotted with respect to elapsedtime.

FIGS. 2A-2C are plots of data recorded during the first test case(Case 1) of packer inflation. FIG. 2A is a plot of packer pressure, inpsi, vs. time elapsed (in seconds). FIG. 2B is a plot of setline valveposition, in percent opened, vs. time elapsed (in seconds). FIG. 2C is aplot of motor speed, in rpm, vs. time elapsed (in seconds). FIGS. 2A-2Cdemonstrate the characteristics of packer inflation using currentschemes, without the adaptive and automated schemes disclosed herein. InCase 1, the specified or desired motor speed is 3000 revolutions perminute (rpm), which is achieved at about 75 seconds, as shown in FIG.2C. With the motor at the desired motor speed, the inflation of thepacker begins at about 75 seconds as well, as indicated in FIG. 2A(“start inflation”). Initially during the inflation, the packers arefree to expand, and the pressure within the packers steadily increases,as is evident form about 75 seconds to about 145 seconds. At about 145seconds, the pressure in the bladders of the packer begins to rise morerapidly than prior to about 145, as shown in FIG. 2A. The desiredpressure of Case 1 is indicated in the broken line in FIG. 2A. Thepacker reaches the desired pressure of 500 psi in about 7-8 secondsafter the occurrence of the increase in the rate of pressure change.That is, at about 152 to 153 seconds, the desired pressure is reached,where the plot of the measured pressure (solid line) intersects with thedesired pressure (broken line). The ramping down of the motor speedoccurs when the desired pressure is reached, such that an overshoot ofpressure occurs (“pressure overshoot”). As used herein, a “desiredpressure” is the pressure at which the bladders of the packers are to beinflated for operations (e.g., for inflation to isolate a wellboresection). As used herein, a “pressure overshoot” refers to an amount ofpressure of the bladders of the packers that is greater than the desiredpressure. For example, if the desired pressure is 500 psi and thebladders are inflated to a pressure of 650 psi, then the pressureovershoot is 150 psi.

As used herein, “onset of restraining” refers to the time at which thebladders are inflated to a point that the bladders are engaged with(e.g., touching) the borehole wall. With the bladders engaged with theborehole wall, the borehole wall restrains the bladders from any furtherfree expansion of the bladders. Without being bound by theory, the onsetof the rapidly rising pressure, occurring at about 145 seconds in FIG.2A, is believed to be indicative of the onset of restraining. From thetime of the onset of restraining, the packer pressure increases rapidlywith pumping (e.g., continuous pumping).

As shown in FIG. 2B, upon the desired pressure being attained, thesetline valve position moves from 100% open to 0% open over a finiteperiod of time. The broken line in FIG. 2C indicates the time at whichthe desired pressure is reached. As is evident from FIG. 2C, the speedof the motor, which is driving the pump, does not begin to slow downuntil the desired pressure is reached. After the desired pressure isreached, the motor speed is continuously or continually reduced untilthe motor is no longer running. As the motor keeps running afterreaching the desired pressure, albeit at a decreasing rate, the motorcorrespondingly keeps driving the pump, albeit at a decreasing rate.Thus, additional fluid is pumped into the bladders of the packer, suchthat the pressure in the packer increases beyond the desired pressure,such that a pressure overshoot occurs.

FIGS. 3A-7C depict similar characteristics of packer inflation for Cases2-6, respectively. However, the data of the test cases of FIGS. 3A-7Cwere obtained in different wells, and the motors in the test cases ofFIGS. 3A-7C were operated at different motor speeds, ranging from 2000rpm to 4000 rpm. As is evident from FIGS. 2A-7C, during packerinflation: (1) the packer pressure increases slowly until the onset ofrestraining occurs; and (2) after the onset of restraining occurs, thepacker pressure increases more rapidly than prior to the onset ofrestraining. Without being bound by theory, it is believed that, withouta proper control of the motor, the packers will experience relativelylarge pressure overshoots, which can deform and damage the packerelements (bladders).

Adaptive and Automated Control Algorithm

In some embodiments, an adaptive and automated control algorithm is usedto control the pumping of fluid into the packer elements, such as bycontrolling the speed of the motor that drives the pump. In some suchembodiments, the adaptive and automated control algorithm is firmwarestored in a non-transitory storage medium. For example, the adaptive andautomated control algorithm may be firmware stored in a non-transitorystorage medium of a motor controller that controls the speed of themotor. The motor controller may be or include a computer that includes aprocessor and non-transitory storage medium, a PLC, a VFD, orcombinations thereof.

With reference to FIG. 8A, in some embodiments a step is to detect theonset of restraining while pumping the fluid into the packers, box 812.The onset of restraining can be detected by monitoring the pressure ofthe bladders, and determining a pressure derivative thereof, asdiscussed in more detail below.

Once the onset of restraining it is detected, control of the speed ofthe motor by the adaptive and automated pressure control algorithm isinitiated, box 814. The adaptive and automated pressure controlalgorithm controls the speed of the motor to prevent the pressure in thebladders from overshooting the desired pressure. As would be understoodby those skilled in the art, the desired pressure may vary with theinflatable packer used; the wellbore, including the size and ambientconditions within the well, and the operation being carried out (e.g.,formatting testing). For example, and without limitation, the desiredpressure may range from 100 to 600 psi, from 200 to 500 psi, or from 300to 400 psi. The desired pressure may be greater than or less than thesepressures, depending on the particular application. Also, once thedesired pressure is reached in the bladders, the algorithm controls thespeed of the motor to maintain the pressure in the packers at thedesired pressure or at about the desired pressure, box 816.

In some embodiments, the onset of restraining is determined using apressure threshold value. That is, once the pressure in the packerexceeds a pressure threshold value, the onset of restraining point isdetermined to have occurred. For example, with reference to FIG. 9Q, theasterisk indicates a pressure threshold value. As used herein, a“pressure threshold value” is a pressure value that is determined to beindicative of the onset of restraining. In some embodiments, thepressure threshold value is predetermined to be indicative of the onsetof restraining. As such, when pressure within the bladders is measuredand determined to be equal to or greater than the pressure thresholdvalue, then reducing the speed of the motor is initiated in order tostop the pumping of fluid into the bladders. The pressure thresholdvalue may be less than the desired pressure.

Without being bound by theory, a method of determining the onset ofrestraining that is believed to be more robust and reliable than usingthe pressure threshold value, is to use a pressure derivative withrespect with time. For example, in some applications, a pressure gaugein the setline may not calibrated well, which can cause bias in themeasured pressure value in the packer. Using the pressure derivative,instead of the pressure threshold value, eliminates offsets and biasesin the pressure measurements, as offsets and biases do not affect thecalculated pressure derivative. In some such embodiments, the pressurederivative is calculated using the Savitzky-Golay polynomial filter. TheSavitzky-Golay polynomial filter is disclosed in: A. Savitzky and M. J.E. Golay, “Smoothing and Differentiation of Data by Simplified LeastSquares Procedures,” Anal. Chem., vol. 36, pp. 1627-1639, 1964.

In some embodiments pressure data of the bladders and/or in the setlineis sampled at random or fixed intervals. With the pressure data sampledat fixed intervals, such as every 64 milliseconds, the Savitzky-Golaypolynomial filter can be pre-calculated and loaded into a buffer fordownhole firmware processing. In one exemplary application, theSavitzky-Golay polynomial filter is designed with a polynomial order oftwo and a filter length of eleven. Such an exemplary Savitzky-Golaypolynomial filter is listed below:

-   -   −0.045455    -   −0.036364    -   −0.027273    -   −0.018182    -   −0.0090909    -   0.0    -   0.0090909    -   0.018182    -   0.027273    -   0.036364    -   0.045455

The above exemplary Savitzky-Golay polynomial filter is anti-symmetricwith respect to the middle point (=0.0).

FIG. 8B depicts another simplified flow diagram of the method ofinflating a packer disclosed herein. The method includes setting thepacker in a wellbore, box 802, and beginning the inflation of thepacker, box 804. The method includes monitoring the pressure within thesetline, box 806, and determining a pressure derivative of the monitoredpressure, over time, box 808. The method includes comparing themonitored pressure to a pressure threshold and comparing the pressurederivative to a derivative threshold, box 810. When the monitoredpressure is equal to or greater than the pressure threshold and thepressure derivative is equal to or greater than the derivativethreshold, the onset of restraining is detected, box 812. When the onsetof restraining is detected, the method includes initiating control ofthe motor using the adaptive and automated pressure control algorithm,box 814. After initiation of the algorithm, the method includesmaintaining the pressure at or near the desired pressure, box 816.

The pressure derivative obtained by applying the Savitzky-Golaypolynomial filter to the collected pressure data for Cases 1-6,respectively, are shown in FIGS. 9A-14B, respectively.

FIG. 9A is a graph of the packer pressure of Case 1 showing the detectedonset of restraining, indicated by an asterisk. FIG. 9B is a graph ofthe pressure derivative obtained by applying the Savitzky-Golaypolynomial filter to the pressure data in Case 1. Pressure over time(psi/seconds) is plotted versus elapsed time (seconds) in FIG. 9B. InFIG. 9B, the solid line is the plot of the pressure derivative, and thebroken line indicates the threshold value. The threshold value is 10psi/sec. The onset of restraining is detected and determined when thecalculated pressure derivative exceeds the threshold value. Thethreshold value of 10 psi/sec was found to be robust and suitable forall of Cases 1-6. That is, prior to the onset of restraining, thepressure derivative was found to remain below or essentially below therate of 10 psi/sec. The detected onset of restraining indicates the timeat which the adaptive pressure control algorithm is initiated. That is,once the pressure derivative exceeds the threshold value, the algorithminstructs the variable frequency drive to begin reducing the speed ofthe motor to, thereby, reduce the rate of the pumping of fluid into thebladders of the packer.

FIG. 10A is a graph of the packer pressure of Case 2 showing thedetected onset of restraining, indicated by an asterisk. FIG. 10B is agraph of the pressure derivative obtained by applying the Savitzky-Golaypolynomial filter to the pressure data in Case 2.

FIG. 11A is a graph of the packer pressure of Case 3 showing thedetected onset of restraining, indicated by an asterisk. FIG. 11B is agraph of the pressure derivative obtained by applying the Savitzky-Golaypolynomial filter to the pressure data in Case 3.

FIG. 12A is a graph of the packer pressure of Case 4 showing thedetected onset of restraining, indicated by an asterisk. FIG. 12B is agraph of the pressure derivative obtained by applying the Savitzky-Golaypolynomial filter to the pressure data in Case 4.

FIG. 13A is a graph of the packer pressure of Case 5 showing thedetected onset of restraining, indicated by an asterisk. FIG. 13B is agraph of the pressure derivative obtained by applying the Savitzky-Golaypolynomial filter to the pressure data in Case 5.

FIG. 14A is a graph of the packer pressure of Case 6 showing thedetected onset of restraining, indicated by an asterisk. FIG. 14B is agraph of the pressure derivative obtained by applying the Savitzky-Golaypolynomial filter to the pressure data in Case 6.

The adaptive and automated pressure control algorithm is a proportionalcontrol scheme in accordance with the following equation (Equation 1):

$\begin{matrix}{\omega = {{\frac{p_{d} - p}{P_{d} - P^{*}}\omega_{d}} + \omega_{c}}} & (1)\end{matrix}$

In Equation 1, p_(d) and ω_(d) are the desired pressure and specifiedmotor speed at the beginning of pumping (time=0 seconds), respectively.Further, in Equation 1, p* is the pressure at the detected onset ofrestraining and ω_(c) is a constant speed to maintain the motor inaction. The adaptive and automated pressure control algorithm scheme inEquation (1) is applied after the detection of the onset of restraining.Therefore, the required motor speed ω, which is calculated using thepacker measured pressure p, begins reducing proportionally after thedetection of the onset of restraining is confirmed. Once the measuredpressure p reaches the desired pressure p_(d), the first term on theright-hand side of Equation (1) is zero and the motor, thereafter, isoperated at the constant speed ω_(c), which is a motor speed that isconfigured to compensate for decay in the packer pressure, as shown inthe graphs associated with Cases 1-6 after the motor is stopped.

Real-Time Implementation

In some embodiments, the adaptive and automated pressure controlalgorithm is implemented in real-time in downhole firmware. That is, theonset of restraining is detected in real-time, during the inflating ofthe inflatable packer. With reference to FIG. 15, a flow diagram of oneexemplary implementation of the adaptive and automated pressure controlalgorithm 1500 disclosed herein is shown. A block 1502, detection ofonset of restraining occurs. If, at block 1502, the onset of restrainingis not detected, then the motor speed of the motor 1506 that drives thepump is set as the specified speed 1504, cod. If, at block 1502, theonset of restraining is detected, then parameters 1508 are used tocalculate the motor speed based on Equation (1) 1510, and thiscalculated motor speed is used to drive the pump. The onset ofrestraining is determined using the Savitzky-Golay polynomial filter. Asshown, pressure measurements from setline pressure gauge 1512, whichdetermines the measured pressure, are compared with the desired pressureat 1514.

With reference to FIG. 16, a flow diagram of another exemplaryimplementation of the adaptive and automated pressure control algorithm1600 disclosed herein is shown. In some embodiments, the implementationof the adaptive and automated pressure control algorithm provides acircular buffer of L registers (e.g., L=11). At each sampled time, thebuffer is shifted to let the oldest sample in the leftmost register out(i.e., x(i)=x(i+1), i=1, . . . 10) and to let the rightmost registerfill with the newest sample (i.e., x(11)=new sample). That is, aregister of the 11 most recent pressure measurements taken by thesetline pressure gauge are maintained. Subsequently, the inner productof the buffer content is determined using the Savitzky-Golay polynomialfilter, which is pre-stored as a portion of the firmware, in accordancewith the following equation (Equation 2):

D=Σ _(i=1) ^(i=11) x(i)f(i)  (2)

In Equation 2, f(i) is the Savitzky-Golay polynomial filter and D is thecalculated pressure derivative. The calculated pressure derivative isthe derivative at the 5-sample point (i.e., half-length ofSavitzky-Golay polynomial filter). With the pressure data sampled at 64millisecond intervals, the detection of the onset of restraining isdelayed by about 0.3 second (i.e., 5×64 milliseconds≈0.3 seconds), whichis permissible for certain applications. The detection of the onset ofrestraining is triggered and determined when the pressure derivation(i.e., D) is larger than the derivative threshold (i.e., d_thd) and themeasured pressure (i.e., x(L)) is larger than the pressure threshold(i.e., p_thd). Based on Cases 1-6 disclosed herein, these two thresholds(i.e., the derivative threshold and the pressure threshold) can bereliably set as d_thd=10 psi/sec and p_thd=100 psi.

With reference to FIG. 16, the steps in the flow diagram of the adaptiveand automated pressure control algorithm 1600 will now be described. Thedata buffer is initialized (i.e., x(i)=0, i=1 . . . L), at box 1602.Next, it is determined if certain operating conditions are satisfied, atbox 1604. The operating conditions that are satisfied may be, forexample: (1) setline valve is open; (2) the solenoid for control of thesetline valve tuned on; and (3) the motor speed is greater than 0 rpm.If the operating conditions are not satisfied, then, at the next timestep, the operating conditions are checked again, box 1606. Thereal-time packer pressure data is collected, box 1608, and input intothe data buffer, box 1610. The Savitzky-Golay polynomial filter, box1612, is applied to the data of the data buffer to calculate thepressure derivative, box 1614. The pressure derivative is compared withthe pressure derivative threshold and the measured pressure is comparedwith the pressure threshold, box 1616. If the pressure derivative islower than the pressure derivative threshold or the measured pressure islower than the pressure threshold, then the calculation is performedagain at the next time step, box 1618. If the pressure derivative is ator higher than the pressure derivative threshold and the measuredpressure is at or higher than the pressure threshold, then the onset ofrestraining is detected, box 1620. If the onset of restraining isdetected, then the adaptive and automated pressure control algorithm isinitiated at the next time step to control the motor and, thereby,control the pumping up of the packers and the pressure thereof, box1622.

As would be clear in view of the above discussions, the systems,methods, and apparatus disclosed herein provide for the inflation ofpackers such that the occurrence of pressure overshoot is reduced oreliminated. While described with reference to the inflation ofinflatable packers, the systems, methods, and apparatus disclosed hereinmay be used in other applications where inflation is used.

Computer Readable Medium

Some embodiments include a computer readable medium (e.g., a datastorage, such as a computer hard drive) that can be configured to causea processor in communication therewith to executed algorithms for themonitoring and/or control of the inflation of inflatable packers. Forexample, the computer readable medium may be configured to cause aprocessor in communication therewith to monitor the pressure of theinflatable element, determine of a derivative of the monitored pressure,and execute the pressure control algorithm disclosed herein.

In some embodiments, the computer readable medium (e.g., anon-transitory storage medium) is in communication with a processor. Thecomputer readable medium includes processor-executable instructionsstored thereon (e.g., as firmware) that are configured to instruct theprocessor to execute the pressure control algorithm to control a speedof a motor in response to pressure measurement data. Theprocessor-executable instructions stored on the computer readable mediummay include: (1) processor-executable instructions that instruct theprocessor to receive the pressure measurement data from a pressuresensor positioned to measure pressure of an inflatable element of theinflatable packer; (2) processor-executable instructions that instructthe processor to determine a derivative of the pressure measurement datawith respect to time; and (3) processor-executable instructions thatinstruct the processor to determine a motor speed of a motor that drivesa pump that inflates the inflatable element, based on the pressuremeasurement data and the derivative. In some embodiments, theprocessor-executable instructions include: processor-executableinstructions that instruct the processor to control the speed of themotor, co, in accordance with the following equation:

$\begin{matrix}{\omega = {{\frac{p_{d} - p}{P_{d} - P^{*}}\omega_{d}} + \omega_{c}}} & (1)\end{matrix}$

In the Equation 1, p_(d) is a target pressure of the inflatable element,p is the most recently measured pressure of the inflatable element, p*is the measured pressure of the inflatable element at the time thatonset of restraining is determined, ω_(d) is an initial motor speed, andω_(c) is a constant motor speed to maintain inflation of the inflatableelement after reaching the desired pressure.

In some embodiments, the pressure measurement data includes pressuremeasurements of the inflatable element over time, at fixed intervals,and a buffer of L registers of measured pressure is maintained in thememory, where L is an integral that is equal to or greater than 2 (e.g.,11, or from 2-11). The pressure derivative, D, of the pressuremeasurements, x, is determined in accordance with the followingequation:

D=Σ _(i=1) ^(i=L) x(i)f(i)  (2)

In the Equation 2, f(i) is the Savitzky-Golay polynomial filter.

EMBODIMENTS

Certain, non-limiting, embodiments will now be set forth.

Embodiment 1. A method for setting an inflatable packer, the methodincluding: positioning an inflatable packer within a borehole; pumpingfluid into an inflatable element of the inflatable packer using a pump,wherein the pump is driven by a motor; measuring pressure of theinflatable element; determining a derivative of the measured pressurewith respect to time; determining onset of restraining of the inflatableelement has occurred when the derivative is equal to or greater than aderivative threshold; and upon or after determining the onset ofrestraining, turning off the motor or slowing down an rpm of the motor.

Embodiment 2. The method of embodiment 1, wherein the onset ofrestraining is a time at or after engagement of the inflatable elementwith a wall of the borehole.

Embodiment 3. The method of embodiment 1 or 2, further includingmaintaining the pressure of the inflatable element at or about thepressure threshold.

Embodiment 4. The method of any of embodiments 1 to 3, wherein thederivative is calculated using a Savitzky-Golay polynomial filter.

Embodiment 5. The method of any of embodiments 1 to 4, whereindetermining onset of restraining of the inflatable element has occurredwhen the derivative is equal to or greater than the derivative thresholdand the measured pressure is equal to or greater than a pressurethreshold.

Embodiment 6. The method of embodiment 5, wherein the derivativethreshold is 10 psi/sec or less, and wherein the pressure threshold is100 psi or less.

Embodiment 7. The method of any of embodiments 1 to 6, wherein upon orafter determining the onset of restraining, a pressure control algorithmis used to control the speed of the motor, wherein the pressure controlalgorithm determines a required speed of the motor, co, in accordancewith the following equation:

${\omega = {{\frac{p_{d} - p}{P_{d} - P^{*}}\omega_{d}} + \omega_{c}}},$

wherein p_(d) is a target pressure of the inflatable element, p is themost recently measured pressure of the inflatable element, p* is themeasured pressure of the inflatable element at the time that onset ofrestraining is determined, ω_(d) is an initial motor speed at thebeginning of the pumping of the fluid, and ω_(c) is a motor speed tomaintain inflation of the inflatable element.

Embodiment 8. The method of any of embodiments 1 to 7, wherein thepressure of the inflatable element is measured over time, at fixedintervals, and wherein a buffer of L registers of measured pressure ismaintained, wherein L is an integral that is equal to or greater than 2.

Embodiment 9. The method of embodiment 8, wherein the pressurederivative, D, of the pressure measurements, x, is determined inaccordance with the following equation: D=Σ_(i=1) ^(i=L)x(i)f(i),wherein f(i) is the Savitzky-Golay polynomial filter.

Embodiment 10. The method of any of embodiments 1 to 9, wherein themotor is an electric motor coupled with a variable frequency drive, andwherein controlling the speed of the motor includes controlling avoltage applied to the motor using the variable frequency drive.

Embodiment 11. A system for setting an inflatable packer, the systemincluding: an inflatable packer, including an inflatable element; a pumpin fluid communication with the inflatable element; a motor, wherein themotor is coupled with the pump to drive the pump; a pressure sensorbetween the pump and the inflatable element, the pressure sensorpositioned to measure pressure of the inflatable element; and a motorcontroller coupled with the motor, the motor controller including aprocessor, a computer readable medium in communication with theprocessor, and processor-executable instructions stored on the computerreadable medium that instruct the processor to execute a pressurecontrol algorithm to control a speed of the motor in response topressure measurement data from the pressure sensor.

Embodiment 12. The system of embodiment 11, wherein theprocessor-executable instructions include: processor-executableinstructions that instruct the processor to determine a derivative ofthe pressure measured by the pressure sensor with respect to time, andto compare the derivative to a derivative threshold;processor-executable instructions that instruct the processor to comparethe pressure measured by the pressure sensor to a pressure threshold;and processor-executable instructions that instruct the processor to,when the derivative is equal to or greater than the derivative thresholdand when the pressure measured is equal to or greater than the pressurethreshold, determine onset of restraining and turn off or slowdown themotor.

Embodiment 13. The system of embodiment 11 or 12, wherein the motor isan electric motor, and wherein the motor controller includes a variablefrequency drive.

Embodiment 14. The system of any of embodiments 11 to 13, wherein theprocessor-executable instructions include processor-executableinstructions that instruct the processor to maintain the pressure of theinflatable element at or about the pressure threshold after the onset ofrestraining.

Embodiment 15. The system of any of embodiments 11 to 14, wherein theprocessor-executable instructions including processor-executableinstructions that instruct the processor to calculate the derivativeusing a Savitzky-Golay polynomial filter.

Embodiment 16. The system of any of embodiments 11 to 15, wherein thederivative threshold is 10 psi/sec or less, and wherein the pressurethreshold is 100 psi or less.

Embodiment 17. The system of any of embodiments 11 to 16, wherein theprocessor-executable instructions include processor-executableinstructions that instruct the processor to control the speed of themotor, ω, in accordance with the following equation:

${\omega = {{\frac{p_{d} - p}{P_{d} - P^{*}}\omega_{d}} + \omega_{c}}},$

wherein p_(d) is a target pressure of the inflatable element, p is themost recently measured pressure of the inflatable element, p* is themeasured pressure of the inflatable element at the time that onset ofrestraining is determined, ω_(d) is an initial motor speed, and ω_(c) isa motor speed to maintain inflation of the inflatable element after theonset of restraining.

Embodiment 18. The system of any of embodiments 11 to 17, wherein thepressure sensor measures the pressure of the inflatable element overtime, at fixed intervals, and wherein a buffer of L registers ofmeasured pressure is stored in the computer readable medium, wherein Lis an integral that is equal to or greater than 2; and wherein thepressure derivative, D, of the pressure measurements, x, is determinedin accordance with the following equation: D=Σ_(i=1) ^(i=L)x(i)f(i),wherein f(i) is the Savitzky-Golay polynomial filter.

Embodiment 19. A system for setting an inflatable packer, the systemincluding: a computer readable medium; and processor-executableinstructions stored on the computer readable medium that are configuredto instruct a processor to execute a pressure control algorithm tocontrol a speed of a motor in response to pressure measurement data.

Embodiment 20. The system of embodiment 19, wherein theprocessor-executable instructions stored on the computer readable mediuminclude: processor-executable instructions that instruct the processorto receive the pressure measurement data from a pressure sensorpositioned to measure pressure of an inflatable element of theinflatable packer; processor-executable instructions that instruct theprocessor to determine a derivative of the pressure measurement datawith respect to time; and processor-executable instructions thatinstruct the processor to determine a motor speed of a motor that drivesa pump that inflates the inflatable element, based on the pressuremeasurement data and the derivative.

Embodiment 21. The system of embodiment 20, wherein theprocessor-executable instructions that instruct the processor todetermine the motor speed of the motor that drives the pump thatinflates the inflatable element, based on the pressure measurement dataand the derivative includes: processor-executable instructions thatinstruct the processor to control the speed of the motor, co, inaccordance with the following equation:

${\omega = {{\frac{p_{d} - p}{P_{d} - P^{*}}\omega_{d}} + \omega_{c}}},$

wherein p_(d) is a target pressure of the inflatable element, p is themost recently measured pressure of the inflatable element, p* is themeasured pressure of the inflatable element at the time that onset ofrestraining is determined, ω_(d) is an initial motor speed, and ω_(c) isa motor speed to maintain inflation of the inflatable element after theonset of restraining.

Embodiment 22. The system of embodiment 20 or 21, wherein the pressuremeasurement data includes pressure measurements of the inflatableelement over time, at fixed intervals, and wherein a buffer of Lregisters of measured pressure is maintained in the memory, wherein L isan integral that is equal to or greater than 2; and wherein the pressurederivative, D, of the pressure measurements, x, is determined inaccordance with the following equation: D=Σ_(i=1) ^(i=L)x(i)f(i),wherein f(i) is the Savitzky-Golay polynomial filter.

Although the present embodiments and advantages have been described indetail, it should be understood that various changes, substitutions andalterations can be made herein without departing from the spirit andscope of the disclosure. Moreover, the scope of the present applicationis not intended to be limited to the particular embodiments of theprocesses, machines, manufactures, apparatus, systems, compositions ofmatter, means, methods and steps described in the specification. As oneof ordinary skill in the art will readily appreciate from thedisclosure, processes, machines, manufactures, apparatus, systems,compositions of matter, means, methods, or steps, presently existing orlater to be developed that perform substantially the same function orachieve substantially the same result as the corresponding embodimentsdescribed herein may be utilized according to the present disclosure.Accordingly, the appended claims are intended to include within theirscope such processes, machines, manufactures, apparatus, systems,compositions of matter, means, methods, or steps.

What is claimed is:
 1. A method for setting an inflatable packer, themethod comprising: positioning an inflatable packer within a borehole;pumping fluid into an inflatable element of the inflatable packer usinga pump, wherein the pump is driven by a motor; measuring pressure of theinflatable element; determining a derivative of the measured pressurewith respect to time; determining onset of restraining of the inflatableelement has occurred when the derivative is equal to or greater than aderivative threshold; and upon or after determining the onset ofrestraining, turning off the motor or slowing down an rpm of the motor.2. The method of claim 1, wherein the onset of restraining is a time ator after engagement of the inflatable element with a wall of theborehole.
 3. The method of claim 1, further comprising maintaining thepressure of the inflatable element at or about the pressure threshold.4. The method of claim 1, wherein the derivative is calculated using aSavitzky-Golay polynomial filter.
 5. The method of claim 1, whereindetermining onset of restraining of the inflatable element has occurredwhen the derivative is equal to or greater than the derivative thresholdand the measured pressure is equal to or greater than a pressurethreshold.
 6. The method of claim 5, wherein the derivative threshold is10 psi/sec or less, and wherein the pressure threshold is 100 psi orless.
 7. The method of claim 1, wherein upon or after determining theonset of restraining, a pressure control algorithm is used to controlthe speed of the motor, wherein the pressure control algorithmdetermines a required speed of the motor, ω, in accordance with thefollowing equation:$\omega = {{\frac{p_{d} - p}{P_{d} - P^{*}}\omega_{d}} + \omega_{c}}$wherein p_(d) is a target pressure of the inflatable element, p is themost recently measured pressure of the inflatable element, p* is themeasured pressure of the inflatable element at the time that onset ofrestraining is determined, ω_(d) is an initial motor speed at thebeginning of the pumping of the fluid, and ω_(c) is a motor speed tomaintain inflation of the inflatable element.
 8. The method of claim 1,wherein the pressure of the inflatable element is measured over time, atfixed intervals, and wherein a buffer of L registers of measuredpressure is maintained, wherein L is an integral that is equal to orgreater than
 2. 9. The method of claim 8, wherein the pressurederivative, D, of the pressure measurements, x, is determined inaccordance with the following equation:D=Σ _(i=1) ^(i=L) x(i)f(i) wherein f(i) is the Savitzky-Golay polynomialfilter.
 10. The method of claim 1, wherein the motor is an electricmotor coupled with a variable frequency drive, and wherein controllingthe speed of the motor includes controlling a voltage applied to themotor using the variable frequency drive.
 11. A system for setting aninflatable packer, the system comprising: an inflatable packer,including an inflatable element; a pump in fluid communication with theinflatable element; a motor, wherein the motor is coupled with the pumpto drive the pump; a pressure sensor between the pump and the inflatableelement, the pressure sensor positioned to measure pressure of theinflatable element; and a motor controller coupled with the motor, themotor controller including a processor, a computer readable medium incommunication with the processor, and processor-executable instructionsstored on the computer readable medium that instruct the processor toexecute a pressure control algorithm to control a speed of the motor inresponse to pressure measurement data from the pressure sensor.
 12. Thesystem of claim 11, wherein the processor-executable instructionsinclude: processor-executable instructions that instruct the processorto determine a derivative of the pressure measured by the pressuresensor with respect to time, and to compare the derivative to aderivative threshold; processor-executable instructions that instructthe processor to compare the pressure measured by the pressure sensor toa pressure threshold; and processor-executable instructions thatinstruct the processor to, when the derivative is equal to or greaterthan the derivative threshold and when the pressure measured is equal toor greater than the pressure threshold, determine onset of restrainingand turn off or slowdown the motor.
 13. The system of claim 11, whereinthe motor is an electric motor, and wherein the motor controllerincludes a variable frequency drive.
 14. The system of claim 12, whereinthe processor-executable instructions include processor-executableinstructions that instruct the processor to maintain the pressure of theinflatable element at or about the pressure threshold after the onset ofrestraining.
 15. The system of claim 12, wherein theprocessor-executable instructions including processor-executableinstructions that instruct the processor to calculate the derivativeusing a Savitzky-Golay polynomial filter.
 16. The system of claim 12,wherein the derivative threshold is 10 psi/sec or less, and wherein thepressure threshold is 100 psi or less.
 17. The system of claim 11,wherein the processor-executable instructions includeprocessor-executable instructions that instruct the processor to controlthe speed of the motor, ω, in accordance with the following equation:$\omega = {{\frac{p_{d} - p}{P_{d} - P^{*}}\omega_{d}} + \omega_{c}}$wherein p_(d) is a target pressure of the inflatable element, p is themost recently measured pressure of the inflatable element, p* is themeasured pressure of the inflatable element at the time that onset ofrestraining is determined, ω_(d) is an initial motor speed, and ω_(c) isa motor speed to maintain inflation of the inflatable element after theonset of restraining.
 18. The system of claim 11, wherein the pressuresensor measures the pressure of the inflatable element over time, atfixed intervals, and wherein a buffer of L registers of measuredpressure is stored in the computer readable medium, wherein L is anintegral that is equal to or greater than 2; and wherein the pressurederivative, D, of the pressure measurements, x, is determined inaccordance with the following equation:D=Σ _(i=1) ^(i=L) x(i)f(i) wherein f(i) is the Savitzky-Golay polynomialfilter.
 19. A system for setting an inflatable packer, the systemcomprising: a computer readable medium; and processor-executableinstructions stored on the computer readable medium that are configuredto instruct a processor to execute a pressure control algorithm tocontrol a speed of a motor in response to pressure measurement data. 20.The system of claim 19, wherein the processor-executable instructionsstored on the computer readable medium include: processor-executableinstructions that instruct the processor to receive the pressuremeasurement data from a pressure sensor positioned to measure pressureof an inflatable element of the inflatable packer; processor-executableinstructions that instruct the processor to determine a derivative ofthe pressure measurement data with respect to time; andprocessor-executable instructions that instruct the processor todetermine a motor speed of a motor that drives a pump that inflates theinflatable element, based on the pressure measurement data and thederivative.
 21. The system of claim 20, wherein the processor-executableinstructions that instruct the processor to determine the motor speed ofthe motor that drives the pump that inflates the inflatable element,based on the pressure measurement data and the derivative includes:processor-executable instructions that instruct the processor to controlthe speed of the motor, ω, in accordance with the following equation:$\omega = {{\frac{p_{d} - p}{P_{d} - P^{*}}\omega_{d}} + \omega_{c}}$wherein p_(d) is a target pressure of the inflatable element, p is themost recently measured pressure of the inflatable element, p* is themeasured pressure of the inflatable element at the time that onset ofrestraining is determined, ω_(d) is an initial motor speed, and ω_(c) isa motor speed to maintain inflation of the inflatable element after theonset of restraining.
 22. The system of claim 20, wherein the pressuremeasurement data includes pressure measurements of the inflatableelement over time, at fixed intervals, and wherein a buffer of Lregisters of measured pressure is maintained in the memory, wherein L isan integral that is equal to or greater than 2; and wherein the pressurederivative, D, of the pressure measurements, x, is determined inaccordance with the following equation:D=Σ _(i=1) ^(i=L) x(i)f(i) wherein f(i) is the Savitzky-Golay polynomialfilter.